Portable beverage containers are used to hold many types of beverages to include carbonated soft drinks, fruit drinks, and beer. It is well known to provide a protective internal liner for those containers made of metal such as aluminum or steel to help preserve the beverage within the container by preventing undesirable chemical reactions that would otherwise take place over time by direct contact of the beverage with the metallic container. For containers made of plastic, there is typically no internal liner provided because the plastic material is inherently non-reactive with respect to most types of beverages.
Many beverages are preferably consumed at relatively cold temperatures, for example, between about 36° F. and 50° F. For carbonated soft drinks and beer, consumers typically prefer these beverages to be chilled prior to consumption. Traditional chilling or cooling techniques include placing the containers in a chilled environment such as a refrigerator or cooler, and then serving the beverage once the beverage has reached a desired chilled temperature.
When the beverage is removed from the chilled environment, the beverage begins to quickly warm due to a combination of external heat sources including ambient heat of the surrounding environment, contact with warm surfaces such as the consumer's hand or the surface on which the container is placed, as well as radiant heat from the sun or other light sources. Heat transfer takes place through the walls, base, and top of the container to the beverage. Without some means provided for insulating the container, the beverage so quickly warms that, in many circumstances, it becomes undesirable or unfit for consumption.
There are a number of inventions that have been developed for purposes of insulating a beverage within the container such that it is maintained at a desired temperature prior to and during consumption. For example, it is well known to provide external thermal barriers, such as an insulating sleeve that is applied over the exterior sidewall of the container. It is also known to provide an insulated label on the sidewall of the container. There are a number of disadvantages to these traditional methods of insulating beverages. An insulating label/sleeve only covers the container sidewall, therefore leaving the bottom of the container exposed. For insulated labels, they are typically much thicker than a non-insulated label and, therefore, standard packaging line may have to be substantially modified to accommodate these special labels. For insulating sleeves, these require the consumer to maintain a separate component to maintain the beverage at a desired cold temperature.
Some efforts have been made to provide an internal insulating liner for containers. One example is disclosed in U.S. Pat. No. 6,474,498. This reference discloses a thermally insulated container for canned beverages including a lining formed from a plastics material. The preferred embodiments suggest using a plastic closed cell material to include closed cell material similar to bubble wrap. The liner is intended to be placed into the container as by a slidable fit within the container so as to be in contact with the cylindrical inner surface of the container wall. The lining member may include an adherent surface allowing the lining to adhere to the internal wall of the container. In an alternative embodiment, this reference discloses a closed cell material that can be provided as a layer on the interior surface of the metal container in addition to or in place of a conventional lacquered coating applied to the interior surface of the container.
U.S. Patent Application Publication No. 2006-0073298 discloses a multi-layer inner liner provided for a container and an extrusion method for a beverage container. The method contemplates blow molding the inner liner by co-extrusion of a first inner layer of a thermoplastics material and a second inner layer made of a foam material having insulating properties. The inner layer of foam is further disclosed as having micro-spheres that expand during the blow-molding process.
U.S. Patent Application Publication No. 2006-0054622 discloses an insulated beverage container having an inner liner that adheres to the inside of the container. The inner liner is made from a crystalline ceramic material.
While the foregoing references may be adequate for their intended purpose, there is still a need for an internal thermal barrier to maintain a beverage at a desired temperature wherein the thermal barrier can be incorporated within a liner installed by using standard packaging machinery.